(n,m,o,p) = map(float, raw_input().split())
print ((n-o)**2 + (m-p)**2)**0.5 (n,m,o,p) = map(float, raw_input().split()) (n,m,o,p) n m o p map(float, raw_input().split()) map float raw_input().split() ().split () raw_input split print ((n-o)**2 + (m-p)**2)**0.5 print ((n-o)**2 + (m-p)**2) print (n-o)**2 + (m-p)**2 (n-o)**2 n-o n o 2 (m-p)**2 m-p m p 2 0.5
(n,m,o,p) = map(float, raw_input().split())
print ((n-o)**2 + (m-p)**2)**0.5